Impulse driving apparatus

ABSTRACT

An impulse driving apparatus, for use for example in pile driving, in which a plurality of striker members are released from a given height above an object to which impulses are to be given in such a way that the stricker members deliver impulses to the object either simultaneously or at pre-determined intervals of time.

Umted States Patent 1191 1111 3,828,866 Jansz [fil -Aug. 13, 1974 1IMPULSE DRIVING APPARATUS 2,798,363 7/1957 Hazak et al 173/118 x3,096,831 7/1963 Adams 173/127 [75] lnvemo Werner Jan, The Hague3,305,034 2/1967 Koeln 173/102 x Nethfllands 3,559,751 2/1971 Yamada173/118 AssigneeZ o a ds Beton G p N v Evans Rijswijk Z.h., Netherlands[22] Fil d; A g, 14, 1972 Primary ExaminerErnest R. Purser pp 280 412Attorney, Agent, or Firm-Brisebois & Kruger [30] Foreign ApplicationPriority Data ABSTRACT Sept. 9, 1971 Great Britain 42192/71 An impulsedriving apparatus, for use for example in [52] U.S.l1 173/101, 173/1,l73DlG. 1 pile driving in which a plurality of Striker members [51] Int.1 E0 (1 7/10 are released from a given height above an Object to [58]held of Search 173/1 which impulses are to be given in such a way thatthe 173/127 1 l8 stricker members deliver impulses to the object eitherReferences Cited simultaneously or at pre-determined intervals of time.UNITED STATES PATENTS 7 Claims, 12 Drawing Figures 1,958,041 5/1934Hansen 173/D1G. 1

1 IMPULSE DRIVING APPARATUS This invention relates to impulse drivingapparatus and methods which have particular, though not exclusive,application in driving objects, for example piles, into the ground.

The apparatus of the present invention enables larger amounts of energyto be available in one unit, for driving an object, such as a pile, intothe ground, than have previously been obtainable.

It is not possible simply to increase the size of known apparatus inorder to make available larger amounts of energy due, inter alia, tomanufacturing difficulties in heat treating and handling large parts.

According to one aspect of the present invention there is provided animpulse driving apparatus including a plurality of hammer members eacharranged to deliver an impulse to an object in response to a signal,

a cylinder, a piston in the cylinder carrying a rod coupled to thehammer members, means whereby the piston and a face of each of thehammer members can each be raised to a respective height abovean objectto which impulses are to be given and means to release the piston inresponse to the said signal thereby to allow each hammer member to falland to deliver an impulse to an object.

According to another aspect of the invention there is provided a methodof operating an impulse driving apparatus as described above wherein thehammer members impact upon the object substantially simultaneously.

According to yet another aspect of the present invention there isprovided a method of operating an impulse driving apparatus as describedabove wherein the hammer members impact upon the object at successivepredetermined intervals of time.

Embodiments of the invention will now be described with reference to theaccompanying drawings in which:

FIG. 1 is a partially cut-away longitudinal section through a piledriving apparatus,

FIG. 2 is a cross-section on the line II-II of FIG. 1,

FIG. 3 is a cross-section at a similar point on another embodiment of apile driving apparatus,

FIG. 4 represents at (a)(b)(c) and (d) the force-time diagrams ofdifferent pile driving apparatus,

FIG. 5 represents at (a)(b)(c)(d) and (e) respectively the force-timediagrams of further pile driving apparatus.

Referring to FIGS. 1 and 2 there is shown an apparatus which has anouter casing 1 having an end member 2 with a loop 3 from which theapparatus can be suspended above a pile 4 which is to be driven into theground. The apparatus includes a main part 5 which is separated by abulkhead 6 from an upper part 7. The main part 5 houses three impulsedriving or hammer units 8, of which only one is shown in FIG. 1. Theunits 8 are of the type described in our British Pat. Specification No.1,168,547 and US. Pat. No. 3,431,986, in which a chamber containing aprecompressed gas is ar' ranged in the path of a hammer, the gas beingprecompressed to such an extent that the minimum force exceeding theground resistance is directly available under the impact of the hammer.

The units 8 are guided by rods 9 and are each pivotally coupled to aplate 11 at respective points 12. The

plate 11 is pivotally attached at 13 to a piston rod 14, which extendsfrom a piston 15 housed in a cylinder 16 in the upper part 7 of thecasing through the bulkhead 6. The movement of the piston 15 in thecylinder 16 is determined by oil passing through inlet and outlet pipes17, 18 under the control of a unit 19.

Pins 21 having collars 22 pass through the plate 11 to engage the upperend of each of the units 8 and are restrained against movement upwardsby pre-loaded springs 23 acting between the respective collars 22 andhousings 24.

A striker member 25 attached to a piston 55 within the chamber 56 of theunit 8 extends from the lower end of each of the units 8 and engageswith its lower or striker face a cap 26 for a pile. The precompressedgas in the chamber acts between the head of this piston 55 and the head57 of the chamber. The cap 26 is located ina cover 27. A guiding member28 extends from the cover 27 to guide the apparatus on to a pile.

The embodiment shown in FIG. 3 differs from that of FIG. 2 in that ithas four units 8 suspended from a plate 11 instead of three units, butit is operated in a similar manner to the embodiment of FIG. 2.

In operation, oil enters the lower part of the cylinder 16 and raisesthe piston 15 and the assembly including the plate 11 and the units 8 tothe chain dotted position 30. The control unit 19 then operates to causethe piston 15 to fall and allow the plate 11 and the units 8 to falleither under the influence of gravity alone or together with anadditional driving force causing the striker members 25 to hit the cap26 and impact forces to be imparted to the pile 4 from each of the units8 substantially simultaneously. Since the members 25 are arrangedsubstantially on the circumferential arc of the tubular pile 4, theforce is transmitted substantially directly to the pile. The pins 21 actupon their respective units 8 to maintain the units at a common levelwhen they are in the position 30. The springs 23 are of such a strengthand so compressed that when the units are lifted the springs 23 appearto be rigid, the weight acting upon the plate 11 in this conditionbeing, in one particular embodiment, of the order of 10 tons per unit 8.However, the strength and compression of the springs 23 are such thatwhen the respective striker members 25 hit the cap 26 the springs 23 areable to deform without breaking, even though in one particularembodiment the impact force resulting from each of the units 8 is of theorder of 800 tons.

The pins 21 ensure that each of the units 8 is raised to the same levelbefore it is released by tending to correct any tilting of the plate 11about the pivot point 13 of the plate 11 on the piston rod 14, therebymaking more certain that the energy delivered by each unit 8 is the sameand that the time of impact of its striker member 25 on the cap 26 issubstantially the same.

During the operation of the apparatus compressed air can be pumped intothe casing 1 through an inlet nozzle 40 at sufficient pressure toexclude water from the apparatus at whatever level underwater theapparatus is being operated. By operating the apparatus in this pressureequalised condition it is possible to construct the casing 1 lessstrongly than would otherwise be necessary.

In one particular embodiment the duration of the impact force deliveredto the pile by each of the units 8 is five hundredths of a second andthe impacts are delivered within one thousandth of a second of oneanother] Instead of using a spring 23 to provide the resilient deviceother known resilient members can be used.

An idealised diagram of the impact force F against time t for one of theunits 8 is shown in FIG. 4 at (a), where the level of force Fg indicatesthe reaction force of the ground which it is necessary to overcome, andthe level of force Fp, imparted by a particular unit, is the minimumslightly higher force which it is necessary to exert upon the pile inorder to overcome the ground reaction force.

In FIG. 4(b) the force-time diagram of a known steam hammer apparatusshows that to overcome a ground force Fgl the necessary energy is onlyavailable for a time 1 while to overcome a higher ground force Fg2 thenecessary force is only available for an even shorter time The peakforce Fp which is produced by the steam hammer is considerably higherthan that required and could be damaging to the pile.

The diagram of FIG. 4(a) shows the distribution with time of the forceavailable from a diesel operated hammer. This curve also shows a highpeak force Fp which could be damaging to a pile. The first peak, whichis due to the stored energy of the hammer, provides sufficient energy toovercome a ground reaction force Fg2 over a very short time period twhile the time t during which energy is available to overcome a lowerground reaction force Fgl, extends over a longer time period comprisinga part of the period of this first peak and a part of the period of asecond peak resulting from the energy obtained from the combustion offuel in the diesel unit.

In the diagram of FIG. 4(d) there is shown in solid lines thedistribution of energy for a unit according to the embodiment describedwith reference to FIGS. 1 and 2, in which the precompression of the gasin the units 8 is such that the minimum force Fpl, available upon impactfor a time t is just sufficient to overcome a ground resistance forceFgl. To overcome a ground resistance force Fg2, using the same units 8,it is necessary to precompress the gas in the units 8 to a higher level.Since the total amount of energy available is the same, the requiredlevel is reached in thislatter arrangement, as may be seen by the dottedlines, over a shorter time period t Furthermore, as will be seen withreference to FIG. 5, it is possible to apply the impacts from the units8 or from hammers successively and at time intervals which aredetermined by a particular desired distribution with time of the storedenergy and to use either units 8 of the type described in our abovementioned patent specifications or hammers of a type commonly known andused.

In FIG. 5 there is shown in an idealised form at (a) a diagram of theforce available from a single unit 8, and at (b) the forces availablefrom three of the units 8 providing impact forces substantiallysimultaneously with a phase difference t O. The sum of thesesimultaneous impacts is shown in FIG. 5 at (c) to provide an acceptabledistribution of impact force.

It is possible, in accordance with one aspect of the invention employingunits 8, to delay the times of impact of the individual units 8. Theresult of such a method of operation is shown in FIG. 5 at (d) where adelay t 0.9t is provided between the successive times of impact. Theresultant of these successive impacts is shown period of 2.7t.

The invention is not limited to the particular embodiments described andmodifications and variations within the scope of the invention may bemade. For example other methods of raising the plate 11 and the units 8than the hydraulic method employing the piston and cylinder may be used.Where units 8 employing precompressed gas in the path of a hammer areused, the gas can be precompressed under the control of oil pressureapplied via a line which is common to each of the units 8, therebyensuring that the gas in each unit is precompressed to a common value.

I claim:

1. An impulse driving apparatus for driving piles and other objectsincluding a plurality of hammer members mounted for movement in the samedirection and each having a striker face, the striker faces of therespective hammer members being located sideways relative to each otherin the direction perpendicular to the direction of the movement of thehammer members whereby each striker face can independently deliver animpulse to the object to be driven, fluid-operated piston means, meanscoupling said piston means to said hammer members, said coupling meansincluding a plate pivotally connected to the piston means, the hammermembers being respectively connected to'said plate at substantiallyequal distances from and at substantially equally spaced positionsaround said pivotal connection of the plate to the piston means, controlmeans for controlling the supply of operating fluid to said piston meansto cause said hammer members to move away from the object to whichimpulses are to be delivered and thereafter towards said object wherebyeach hammer member delivers an independent impulse to the object by itsrespective striker face.

2. An impulse driving apparatus as claimed in claim 1 having pivotalconnections between the hammer members and the plate.

3. An impulse driving apparatus as claimed in claim 2 includingresilient stop means arranged between the plate and each hammer memberrespectively to maintain each hammer member in a predetermined pivotalposition relative to the plate when it is away from the object.

4. An impulse driving apparatus as claimed in claim 1 including whereineach hammer member comprises a cylinder, a piston within the cylinderattached to a striker member projecting from the cylinder and having astriker face, and a gas under pressure in the cylinder between thepiston attached to the striker member and the end of the said cylinderremote from the striker member.

5. An impulse driving apparatus as claimed in claim 1 for sub-aqueoususe, including a housing within which the apparatus is contained, thehousing having means whereby compressed air can be introduced therein toexclude water from the apparatus.

6. An impulse driving apparatus for driving piles and the like undersub-aqueous conditions, comprising a substantially air-tight housinghaving at its lower end a vertical tubular guide portion which is openat its bottom and serves to guide the apparatus onto and to receive thetop of a pile to be driven, hammer means mounted on guides for verticalmovement within said housing and having a striker face at its lower end,

7. Apparatus as claimed in claim 6, and including a pile cap captivelymounted in said housing for limited vertical movement and positioned torest on the top of a pile inserted in said guide portion and to bestruck by the striker face of said hammer means when in its lowerposition.

1. An impulse driving apparatus for driving piles and other objects including a plurality of hammer members mounted for movement in the same direction and each having a striker face, the striker faces of the respective hammer members being located sideways relative to each other in the direction perpendicular to the direction of the movement of the hammer members whereby each striker face can independently deliver an impulse to the object to be driven, fluid-operated piston means, means coupling said piston means to said hammer members, said coupling means including a plate pivotally connected to the piston means, the hammer members being respectively connected to said plate at substantially equal distances from and at substantially equally spaced positions around said pivotal connection of the plate to the piston means, control means for controlling the supply of operating fluid to said piston means to cause said hammer members to move away from the object to which impulses are to be delivered and thereafter towards said object whereby each hammer member delivers an independent impulse to the object by its respective striker face.
 2. An impulse driving apparatus as claimed in claim 1 having pivotal connections between the hammer members and the plate.
 3. An impulse driving apparatus as claimed in claim 2 including resilient stop means arranged between the plate and each hammer member respectively to maintain each hammer member in a predetermined pivotal position relative to the plate when it is away from the object.
 4. An impulse driving apparatus as claimed in claim 1 including wherein each hammer member comprises a cylinder, a piston within the cylinder attached to a striker member projecting from the cylinder and having a striker face, and a gas under pressure in the cylinder between the piston attached to the striker member and the end of the said cylinder remote from the striker member.
 5. An impulse driving apparatus as claimed in claim 1 for sub-aqueous use, including a housing within which the apparatus is contained, the housing having means whereby compressed air can be introduced therein to exclude water from the apparatus.
 6. An impulse driving apparatus for driving piles and the like under sub-aqueous conditions, comprising a substantially air-tight housing having at its lower end a vertical tubular guide portion which is open at its bottom and serves to guide the apparatus onto and to receive the top of a pile to be driven, hammer means mounted on guides for vertical movement within said housing and having a striker face at its lower end, hydraulically-operated piston means coupled to said hammer means for moving said hammer means between a lower position in which said striker face is above said guide portion and a raised position, control means for controlling the supply of operating fluid to said piston means, and means for introducing compressed air into said housing to exclude water therefrom when the apparatus is submerged.
 7. Apparatus as claimed in claim 6, and including a pile cap captively mounted in said housing for limited vertical movement and positioned to rest on the top of a pile inserted in said guide portion and to be struck by the striker face of said hammer means when in its lower position. 